I am using the child level IPUMS DHS data for Bangladesh data for 1997, 1999, 2000, 2004, 2011, 2014 , particularly interested in hwwhzwho (Wasting) as my dependent variable. There are cases coded as NIU (not in universe) and flagged, and I am unable to figure out what the represent. I have run cross tabs in stata with age of the mother and age of the child, as well as kidalive which showed me that a majority of the NIU cases were because the child is reported to be not alive.
However, there are about 217 NIU cases that I still have not found an explanation for. I also have not found an explanation for flagged cases in the documentation. Understanding these types of missing data will be very helpful for my analysis! Thanks
NIU (not in universe) cases identify respondents who were not asked a particular question (see this FAQ response). The universe for each variable is provided in its universe tab. For example, you can see from the universe statement for CHEB, total children ever born, that men are never asked about the number of births that they have had during their life. Additionally, women who have never been married as well as those under the age of 15 or those 50 and older were also not asked about their total number of births in the Bangladesh 2014 survey. Note that the universe may be different for different countries and years. Moving to HWWHZWHO, the universe for the Bangladesh samples is surviving children under age 5 who were measured as household members and whose co-resident mothers were ever-married female survey respondents age 15-49 (with different years having slightly different age ranges for the co-resident mother).
As you discovered, the majority of NIU cases are for children who are no longer alive (i.e. not surviving children) using KIDALIVE. It turns out that the remaining 217 NIU cases are for children who were not measured as household members (i.e. LINENOKID = 00 “Not listed in household”). Not all the children represented in child records are also listed in their household’s record. You can see in the universe of HWWHZWHO that in samples from 2004 and onward, a requirement of being in universe is that the child was measured as a household member. That means that these kids did not usually live in the household and were not staying there now. It could be the case for instance that the child was living with another family member outside the household and was not available to have their weight taken. I recommend reviewing each component of the universe statement so that it is clear who has information on a particular variable and who is excluded since this may affect your analysis.